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Cosumnes Preserve Field Trip

Since 2003, dedicated Wetland Ecology Laboratory (ESP 155L) students have participated in vegetation distribution surveys of the Big Barn Slough in the Cosumnes River Preserve. Invasive species expansion, biomass sampling methods, leaf area index, and GPS techniques are emphasized.

The Cosumnes River is unique because it is the largest free-flowing river in the highly regulated Central Valley. The rich riparian forest and tidal freshwater marshes are protected under the joint ownership of the Nature Conservancy, Ducks Unlimited, the California Department of Fish and Game and the Bureau of Land Management. Restoration construction of the 1,000 acre preserve occurred between 1989 and 1994. The preserve boasts a large diversity of birds (e.g. sandhill cranes, cormorants, great blue herons etc.) and a productive vegetation cover.

One of the major points of interest has been following the expansion of the invasive Ludwigia peploides var. montevidensis in this small section of the preserve. Also common in this slough are Ludwigia peploides var. peploides, Polygonum hydropiperoides, Typha latifolia, Schoenoplectus acutus, S. californicus, Sagittaria sp, Xanthium stromarium, Salix spp., Populus sp., and Cephalanthus sp.

Over the past 5 years, Ludwigia peploides var. montevidensis cover has increased dramatically, making it one of the most dominant species in the marsh compared to its minor presence in 2003. Changing weather patterns and altered annual water fluctuations have created unusual conditions for the students to ponder. All in the name of learning science!